The Internet enables communication of data and information between users at diverse locations throughout the world virtually instantaneously. The Internet is in widespread use and continues to grow in popularity and utility. Over the years, various systems have been developed to deliver high-speed access to the Internet. For example, some consumers subscribe to digital subscriber line (DSL) service through their local exchange carrier (telephone company) or other service provider. Other consumers gain high-speed connection to the Internet through their cable company or a satellite service provider.
The asymmetric digital subscriber line (ADSL) services that are being deployed throughout the world provide a “user to network interface” or UNI. Conventionally, an ADSL modem is connected to a digital subscriber line access multiplexer (DSLAM) via the UNI. The ADSL service is invoked by provisioning at least one virtual circuit. The virtual circuit needs to be provisioned from end-to-end (source to destination) and involves multiple network elements. The provisioning procedure is tedious and time consuming. Some modems and DSLAMs are configured to default to a single virtual circuit for each end user. In order for the ADSL service to be functional, both the ADSL modem and an associated DSLAM need to have a compatible ATM layer configuration. Existing networks that utilize virtual circuit connections and can be categorized as connection oriented, include but are not limited to asynchronous transfer mode (ATM), frame relay (FR) and multi-protocol label switching (MPLS).
The common network element deployment strategies typically consist of manually provisioning a permanent virtual circuit (PVC), default initializing a PVC, or implementing a signaling connection setup sequence for switched virtual circuits (SVC). The signaling connection setup sequence requires pre-provisioned signaling client/server entities in some of the elements. A combination of the above strategies may also be applied to the access network. The above described deployment strategies are labor intensive and can cause interoperability limitations between different vendor's equipment.
The assignee of the present application has developed a “plug and play” technique for automatically provisioning an ADSL modem. This technique is described in co-pending application Ser. No. 09/833,780, entitled “AUTOMATIC PERMANENT VIRTUAL CIRCUIT CONNECTION ACTIVATION FOR CONNECTION ORIENTED NETWORKS” (the Auto PVC Application). The text of the Auto PVC Application is incorporated herein by reference. The access node provisions the ADSL modem by learning the virtual channel identifier for the modem and creating a translation to a default virtual channel identifier provisioned at the access node.
DSL service is typically provided over an ATM network with a connection between a remote terminal (RT) and a central office terminal (COT). In ATM networks most of the monitoring occurs at the physical layer, meaning that the individual units, e.g. ATM switches, LAN switches, remote terminals, and end units, in the network provide alarms or other error message when problems with physical transmission are determined. However, physical layer monitoring does not monitor the virtual channels at the ATM layer, specifically the queuing, routing and translation functions that provide the virtual channel functionality through different elements in the network. Since ATM and DSL connections have extremely high throughputs the inability to test the channel as a whole or in part can result in missing translation or routing problems that can result in cells being transmitted along incorrect virtual channels.
In addition, ATM utilizes Operations and Maintenance (OAM) layer functions to perform testing at the ATM adaptation layer (AAL). OAM cells are injected to test either virtual paths or provisioned virtual channels and can be sent from the testing apparatus to an end point or can be looped back between any two ATM nodes along the virtual path or virtual channel. However, OAM cells are limited to ATM links in the network and generally require processing capability in each of ATM switches or end units that the OAM cell passes because the cell identity is contained in the cell payload and these cells cannot be readily distinguished from data cells. This increases the cost of the equipment needed for the end points that in turn drives up the overall cost of the ATM system.
The assignee of the present application has provided a solution to this monitoring problem as described in co-pending application Ser. No. 10/093,296, entitled “EMBEDDED CELL LOOPBACK METHOD AND SYSTEM FOR TESTING IN ATM NETWORKS” (the “ECLP application”). The text of the ECLP Application is incorporated herein by reference. Essentially, the ECLP Application provides for testing the functionality of the ATM layer using specially inserted cells. These cells include special codes stored in a field such as the GFC field.
Unfortunately, use of automatic provisioning for ADSL modems as taught in the Auto PVC application in an access node that supports an embedded cell loop-back protocol as taught in the ECLP patent can result in transmission errors. For example, miss-inserted cells may be improperly interpreted as ECLP cells or may be routed improperly when received at the user-network interface.
Therefore, there is a need in the art for improvements to ingress cell processing at the user-network interface in access network equipment.